ON THE PLASTIC ROTATION CONSTANT USED IN STANDARD COD TESTS - AWRA DOCUMENT P4-5A-84, AWRA CONTRACT 93.

The plastic component of the crack opening displacement (COD) is inferred in the standard three-point bend specimen from the plastic displacement measured at the crack mouth with a clip gauge. It is assumed that the two halves of the specimen rotate about a center. Recent experiments have suggested that the value of the rotational constant r//p adopted for the Australian Standard COD test is too small. This note reports results obtained using a more direct method of measuring r//p and concludes by suggesting that the value of r//p in the Australian Standard should be increased.